Residue removal system for belt abrader

ABSTRACT

Improved residue removal ductwork incorporated with a flexible belt abrading machine, such as a belt sander. The ductwork defines an elongate ductwork extending from adjacent the machine&#39;&#39;s material removal zone to a remote collection site. The duct includes a duct expanse and other duct wall structure which extends along and substantially surrounds the machine&#39;&#39;s abrasive belt over a substantial portion of a reach thereof, thereby providing increased exposure of the belt&#39;&#39;s surface to air flow for improved residue removal and longer belt life. In a preferred embodiment, the ductwork includes a plurality of air inlet openings disposed at several locations about the travel path of the belt.

United States Paten 1191 Zuercher June 17, 1975 RESIDUE REMOVAL SYSTEM FOR BELT ABRADER Primary Examiner-Al Lawrence Smith Assistant Examiner-Nicholas P. Godici 5 Inventor g l zuercher Cottage Attorney, Agent or Firm-Kolisch, Hartwell, 1 1 m Dickinson & Stuart [73] Assignee: Kimwood Corporation, Cottage Grove, e, 57 ABSTRACT [22] Filedz I Nov. 1,1 973 Improved 1 residue removal ductwork incorporated 1 21 A L N 411,915 with a flexible belt abrading machine, such as a belt 1 pp sander. The ductw'ork defines an elongate ductwork 1 I extending from adjacent the machine's material re- [52] US. Cl.. 51/135 R; 51/273 mova] one to a remote collection site The duct in- [51] Int. B241) B241) /06 cludes a duct expanse and other duct wall structure Fleld of Search R, 135 BT, which extends along and substantially surrounds the v 51/139, 44/252 R machines abrasive belt over a substantial portion of a reach thereof, thereby providing increased exposure References Cited of the belts surface to air flow for improved residue 1 UNITED STATES PATENTS removal and longer belt life. In a preferred embodi- 2 324 8/1939 Hanna 51/273 "lent, the ductwork includes a plurality of air inlet 212251225 12/1940 McElevey i 51/27 openings disposed at several locations about the travel 2,640,304 6/1953 McEwan 51/273 X path of the belt. 7 2,865,143 12/1958 Goldsmith 51/273 X 6 C 4 D 3,744,189 7/1973 Kakumu 51/268 x rawmg gums ass 5 :5 55 [20 1201 "z 64 112E 47 5 55 50 1065 i 3 ii 49 7? 40 i i PATENTEDJUN 17 I975 L-i, 889,429

SHEET 1 PATENTEDJUN 1 7 I975 RESIDUE REMOVAL SYSTEM FOR BELT ABRADER BACKGROUND OF THE INVENTION The present invention relates generally to flexible belt abrading machines,- such as sanders and abrasive planers, and to residue removalsystems for such machines.

During the operation of single and multiple-belt industrial sanders and related abrading machines, a considerable quantity of particulate residue is produced. Conventionally, this residue is gathered up and conveyed to a remote collection site by a vacuum system. In one form, such a system includes ductwork having one or more inlets disposed near the surface of the machines abrasive belt. In another form, dust-collecting hoods encompassing portions of the belt at the ends of the machine are used. These and similar known designs have a number of drawbacks, however. Mounting of collection ducts or hoods within a sander impairs access to the working parts of the machine and makes it difficult to change belts or make repairs. Ducts having narrow inlet openings often become plugged, compelling frequent shutdowns to remove blockages.

These and other drawbacks associated with known prior art designs have produced a need for an improved system for collecting and conveying away the particulate residue generated by an abrading machine.

A general object of the present invention, therefore, is to provide a removal system which meets the aboveidentified need in a practical and satisfactory manner.

A more specific object of the invention is to provide a simplified residue removal system permitting ready access to the abrasive belt and other working parts of such a machine.

Another object of the invention is to provide a removal system of increased efficiency which maximizes air flow in the work-abrading zone of the machine.

Still another object of the invention is to provide residue removal ductwork which surrounds a machines abrasive belt over a substantial portion of its run, thereby providing increased exposure of the belts surface to the air flow for better residue removal and longer belt life.

Yet another object of the invention is to provide residue removal ductwork which can accommodate repositioning of a belt roll without affecting air flow adjacent the roll.

These and other objects and advantages of the novel residue removal system of the invention will become more apparent as the description which follows is read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic representation of a residue removal system incorporated with a flexible belt abrader;

FIG. 2 is a fragmentary side elevation, partially cut away, of a flexible belt abrader incorporating a system including residue removal ductwork according to the invention;

FIG. 3 is a fragmentary front elevation, partially cut away and partially in section, of the apparatus of FIG. 2; and

FIG. 4 is a fragmentary cross section taken along line 4--4 of FIG. 3.

Referring now to the drawings, and first more specifically to FIG. .1, indicated generally at is a residue removal system according to the invention. In the embodiment shown, system 10 is configured for use with an upright belt abrader 11. For clarity in illustrating the invention, only certain elements of abrader 11 have been included in the figure. Thus, as shown, abrader 11 includes upper and lower spaced-apart pulleys, or rolls, 12, 14, respectively, training an elongate abrasive belt 16. With the application of power to one of the rolls, e.g., lower roll 14, rearward stretch 16a of the belt is driven in the direction indicated by arrow 15. Thus driven, at the lowermost extent of its travel, belt 16 passes through a material removing zone 13 underlying roll 14 wherein material is abraded from a workpiece 18. Thereafter, the belt passes into residue removal ductwork 20. Ductwork 20 is configured to substantially enclose forward stretch 16b of the belt along its path of travel between lower and upper rolls l4, 12, respectively.

At its upper end, ductwork 20 is connected by an elongate duct 22 to the inlet, or suction, side of air mover means, or blower, 24. With blower 24 operating, air is drawn into ductwork 20 through openings adjacent rolls 12 and 14, as indicated by air flow arrows 28, 30, respectively. The openings into ductwork 20 are proportioned in size so that the volume of air entering the ductwork adjacent roll 14 is substantially greater than that entering adjacent roll 12. With such the case, the bulk of the air volume enters system 10 adjacent material removal zone 13, since, as will be appreciated, most of the particulate material generated by the abrading of workpiece 18 leaves the belt at this point. As the abrasive belt moves upward along stretch 16b toward upper roll 12, additional particulate material is loosened from the belt surface and is displaced into the moving air stream. Finally, as belt 16 travels about the perimeter of upper roll 12, the bending of the belt opens the grit material on the belts surface, loosening additional particulate residue which is displaced into the main air stream by the smaller volume of air entering ductwork 20 at 28. The air stream carrying the particulate residue is discharged by blower 24 into a conventional separator-collector 32.

A particular embodiment of the novel ducting system of the invention is illustrated in FIGS. 2 and 3 in connection with a vertical belt abrasive planer 34. It should be noted that portions of the planer not relevant to a description of the invention have been omitted from the drawings for greater clarity.

Planer 34 includes a vertically spaced pair of horizontally disposed pulleys, or rolls, including a lower, or drive roll 36 and an upper, or idler roll 38, training an endless, flexible abrasive-faced belt 40. Belt 40 includes a forward, i;e., to the right in FIG. 2, stretch 40a extending vertically between drive roll 36 and idler roll 38, and a similar rearward stretch 40b. Rolls 36, 38 are supported in position, in a manner to be more fully described, by an elongate cantilever member 42 disposed intermediate the rolls and stretches 40a, 40b of the belt. Cantilever member 42 is anchored adjacent its inner end 42a (FIG. 3) to the planers 5 frame structure (not shown) and extends outwardly (to the left in FIG. 3) substantially the width of the machine. Planer 34 is enclosed along its back or inner side by an inner side wall 44, and along its front or outer side by an outer side wall 46. An elongate, generally rectangular opening 47 in side wall 46 exposes belt 40 and the space surrounding it, termed herein the belt cavity, for access by an operator. Opening 47 is closed off by an outwardly swinging door 48 hinged to side wall 46 at 5 0 (FIG. 2). Door 48 has the profile and sectional configuration generally shown in the drawings. Specifically, as shown in FIGS. 3 and 4, the forward margin of door 48 includes an elongate, vertically disposed inset edge baffle 48a, the function of which will be later explained.

Referring now to FIGS. 2 and 3, an elongate mounting frame 52 is suitably secured to the underside of can tilever member 42. A pair of bearing mounts, inner mount 54 and outer mount 56, are bolted to the respective opposite down-turned ends of the frame as shown. Journaled in mounts 54, 56, respectively, are drive shaft 58 and stub shaft 60 of drive roll 36. Drive shaft 58 extends through a suitable opening side wall 44 for coupling to powering means (not shown), such as an electric motor.

Idler roll 38 is mounted on mounting frame 62 in a similarmanner, with stub shafts 64, 66 journaled in bearing mounts 68, 70, respectively, at the opposite upturned ends of the frame. Mounting frame 62, carrying idler roll 38, is supported above cantilever member 42 by a conventional hydraulic cylinder 72. As best shown in FIG. 3, cylinder 72 is retained within a recess 420 in the upper portion of the cantilever member, and frame 62 is secured about midway of its length to the free end of the cylinders piston rod 74. With the organization described, idler roll 38 is shiftable vertically with respect to drive roll 36 through operation of cylinder 72, providing convenient means for adjusting the tension of belt 40 or for compensating for stretching of the belt with use.

Means is also provided in planer 34 for adjusting the tracking of belt 40 on rolls 36, 38. Referring to FIG. 2, such means includes a small, horizontally disposed hydraulic cylinder 76 positioned above outer end 42b of the cantilever member by mount 78 as shown. Thus mounted, piston rod 80 of cylinder 76 extends forward, substantially normal to the axis of roll 38. Secured to outer end portion 62a of the upper mounting frame is a bracket 82 including an outwardly projecting flange portion 84. As best shown in FIG. 3, portion 84 includes a spaced pair of depending fingers 86 disposed astride piston rod 80. Referring again to FIG. 2, fingers 86 are located lengthwise of rod 80 by an opposing pair of threaded keepers 88. Keepers 88 are spaced apart a distance slightly greater than the thickness of flange portion 84 so that they lightly engage fingers 86. As will be understood, this permits the fingers to move relatively freely with respect to rod 80 in a vertical direction. At the same time, the fingers and the piston rod remain coupled together for movement in a forwardlrearward direction. Accordingly, with operation of cylinder 76 whereby rod 80 is extended or retracted, force 'is applied to bracket 82, causing the upper mounting frame and idler roll 38 to pivot in a horizontal plane about the axis of piston rod 76. By thus varying the angular relationship of rolls 36 and 38, the tracking of belt 40 on the rolls can be adjusted.

Referring now to FIGS. 2 and 3, planer 34 additionally includes means for supporting a workpiece, such as workpiece 90, in contact with the face of abrasive belt 40 .at a material removal site or zone 92 extending along the lower perimeter of drive roll 36. Such means include a support roll 36' underlying drive roll 36 in parallel, spaced relation thereto. In the abrasive planer illustrated in the drawings, support roll 36' is one of a pair of rolls training an opposing abrasive belt 40' for removing material from the lower surface of workpiece simultaneous with the removal of material from the upper surface by belt 40. Support means for workpiece 90 also include upper and lower infeed rolls 94, 94', respectively, and corresponding outfeed rolls 96, 96' disposed, respectively, forward and rearward of rolls 36, 36 as shown in FIG. 2. The infeed and outfeed rolls convey workpiece 90 through the material removal zone underlying drive roll 36 in the direction indicated (to the left). With power applied to drive shaft 58 (FIG. 3), roll 36 drives belt 40 past material removal zone 92 in the direction indicated by arrows 41, or to the right and upwardly, with the belt moving away from zone 92 along outgoing stretch or reach 40a.

Particulate material abraded from the upper surface of workpiece 90 by belt 40 is conveyed away by residue removal ductwork extending from adjacent the material removal site of a remote location. Referring now to FIGS. 2 and 4, such residue removal ductwork includes a substantially upright wall member 98 comprising central wall portion 98a, and parallel, offset marginal wall portions 98b, 98c joined to the central wall portion by wall portions 98d, 98e, respectively. Wall member 98 spans and is joined along its lateral edges to side walls 44, 46 of the planer. Wall portions 98a, 98b, 98c extend substantially parallel to the forward stretch of belt 40, with central wall portion 98a extending substantially the length of the stretch in spaced opposition to the face of the belt. The lower portion of wall member 98, i.e., the portion generally opposite drive roll 36, is curved back toward the roll as shown in FIG. 2.

Still referring to FIG. 2, planer 34 includes an elongate trailing blade unit 100 disposed intermediate drive roll 36 and upper infeed roll 94. Unit 100 comprises an elongate trailing member or blade 102, also referred to as a deflector, having the transverse cross-sectional configuration shown, including a rearward-facing concave portion 102a. Blade 102 is suitably secured to a plurality of transversely spaced, forward-projecting plate members 104 (one shown) mounted for pivotal movement about the axis of shaft 106. Suitable spring means (not shown) biases blade 102 downward, whereby lower lip 10212 of the blade is pressed against the upper surface of workpiece 90 at a location adjacent planer 34s material removal zone. Mounted in the manner described, blade 102 extends along drive roll 36 substantially the length of the roll. As should be evident, concave portion 102a of blade 102 effectively is a continuation of the curved lower portion of wall member 98. Thus, wall member 98 and trailing blade 102 together form a substantially continuous duct expanse extending from adjacent material removal site 92 to the upper margins of side walls 44, 46.

Referring to FIGS. 2-4, residue removal ductwork for planer 34 additionally includes an upright rear baffle plate 108 suitably secured to the forward face of cantilever member 42 and extending along the forward stretch of belt 40, rearward of its face. As shown in FIGS. 3 and 4, baffle plate 108 includes an inner marginal portion 108a extending laterally inward from adjacent the inner edge of belt 40 to side wall 44. Similarly, an outer marginal portion 108b extends laterally outward from adjacent the outer edge of the belt to Referring now to FIGS. 2 and 3, a spaced pair of baffle segments, inner segment 1 10 and outer segment 112, is suitably attached to the forward side of mounting frame 62 laterally inward and outward respectively, of the ends of roll 38. As shown in FIG. 3, segment 110 extends inward from adjacent the inner edge of belt 40 toward side wall 44, and effectively forms an upward continuation of inner marginal portion 108a of baffle plate 108. Similarly, segment 112 extends outward from the outer edge of belt 40 to form an upward continuation of b. Baffle segments 110, 112 each include a flat lower portion 110a, 112a respectively, juxtaposed in overlapping relation with the adjacent marginal portions of baffle plate 108. Each segment also includes a curved upper portion 110b, 112b respectively, which, as shown in FIG. 2, generally follows the peripheral contour of roll 38.

Referring to FIG. 2, the residue removal ductwork for planer 34 further includes an elongate, adjustable baffle 114 extending substantially fully the width of planar 34 between side walls 44, 46. Adjustable baffle 114 is hingedly attached along its upper, forward edge to a transition duct 1 18 at 1 16. The lower, rearward portion of the baffle is pivotally coupled to the inner end of mounting frame 62 by an adjustable length link 120 comprising spherical rod ends 120a, 120b. Mounted in this manner, baffle 114 is swung vertically coincident with vertical shifting of idler roll 38. Moreover, the distance or gap between adjustable baffle 1 14 and the face of belt 40 remains substantially constant throughout the range of movement of roll 38. By way of illustration, with idler roll 38 shifted vertically to the location shown in phantom outline at 38A, the adjustable baffle is swung upward to the location indicated at 114A.

Disposed atop abrasive planer 34 for connecting the ductwork within the planer to a transferral duct 122 is previously mentioned transition duct 118. Duct 118 includes a lower portion 119 having an elongate, generally rectangular cross-sectional configuration matching that defined by wall member 98, the upper edge of adjustable baffle 114, and side walls 44, 46. At its upper end, duct 118 has a circular cross section matching that of duct 122. As will be understood, duct 122 is connected at its remote end to the inlet or suction side of a blower (not shown).

There is thus provided an elongate residue removal ductwork for planer 34 which extends from adjacent the planers material removal site to a remote location, and which includes a substantially enclosed elongate course extending along and including the forward stretch of the belt. For example, referring to FIGS. 2 and 4, such a course is defined by central wall portion 98a of wall member 98, and deflector 102, forming a duct expanse which is the forward wall of the course, and belt stretch 40a, forming the rearward wall of the course. Duct wall structure including wall portions 98b, 98d, side wall 44 and baffle plate portion 108a effectively form an inner side wall for the course. In like manner, wall portions 98a, 98c, door baffle 48a, and baffle plate portion 108]; form the outer side wall. Upon operation of the blower referred to above, air is drawn into the lower end of the ductwork through openings adjacent either end of drive roll 36. Air entering one such opening is indicated generally in FIG. 1 by arrow 30. As will be understood, the air streams entering the duct at its lower end capture particulate material abraded from workpiece 90 at the work removal site and carry it upward along the forward stretch of the belt.

Air is also drawn into the ductwork through the gap between adjustable baffle 114 and the adjacent, confronting portion of belt 40 and baffle segments 110, 1 12. Air entering at this point passes over the traveling belt surface in a direction opposite to the direction of belt travel, as generally indicated in FIG. 2 by arrow 124. The gap between baffle 114 and the face of belt 40 is preferably adjusted so that the volume of air entering at 124 is substantially smaller than the volume entering the lower end of the duct adjacent the work removal zone, where most of the particulate material leaves the belt. If desired, an additional air inlet opening may be provided between the lower edge of wall member 98 and the upper surface of blade 102 as indicated at 126.

Air entering the ductwork at the above-described locations travels upward into a transition or exhausting duct 118. It will be noted that the transition duct is located substantially in alignment with forward stretch 40a of the abrasive-faced belt, so that the stream of air moving upward along the stretch, which stream carries the bulk of the particulate residue, is smoothly directed into transferral duct 122.

Residue removal ductwork according to the invention provides a number of advantages over prior art designs. For example, the forward stretch of the abrasivefaced belt, which effectively forms a major wall segment of the residue removal duct, typically travels at several thousand surface feet per minute. This moving frictional surface augments movement of air upward through the duct and provides reduced surface drag compared with a stationary duct wall.

Further, the provision of ductwork extending substantially the length of the forward stretch of the belt provides an increased length of exposure of the belts surface to the moving air stream. This allows a maximum opportunity for particulate matter to be displaced into the moving air stream and provides increased belt life through better cooling of the belts surface.

Still further, by utilizing a portion of access door 48 as a side wall component of the residue removal duct, access to the interior of the duct, as well as all of the working parts of the machine within the belt cavity, is provided merely by opening the door. Any accumulated particulate or other foreign material can be quickly and easily removed, minimizing the length and frequency of production shutdowns. In addition, the abrasive-faced belt may be changed easily without the necessity of removing any of the ductwork.

Although a preferred embodiment of the invention has been described herein, it is understood that variations and modifications are possible without departing from the spirit of the invention. For example, air under pressure could be introduced into the duct inlet openings, rather than using remotely located suction means.

It is claimed and desired to secure by Letters Patent:

1. In combination with a flexible belt abrader including an endless belt with an abrasive material-removing outer face and roll support for such belt comprising a pair of spaced rolls having the belt trained thereover,

means for guiding a workpiece against said belt in a zone of the belt adjacent where such belt is supported by one of said rolls,

power-driven means for rotating the roll support for the belt whereby the belt travels from said zone and away from said one roll in an outgoing reach extending to the other of said rolls,

residue removal ductwork comprising a duct expanse extending the length of said outgoing reach in spaced opposition to the outer face of the belt and forming a forward wall in said removal ductwork, wall structure disposed parallel to the rear of the belt in said outgoing reach and forming arear wall in said ductwork, and additional side wall structure I extending between said forward and rear walls to form a substantially enclosed course which encompasses said outgoing reach of theibelt, said residue removal ductwork including an opening adjacent said zone for the inflow of air into said ductwork andanother opening adjacent said other roll to accommodate additional flow of air into said ductwork, said other opening being defined by an adjustable baffle, said other roll being supported on an adjustable mounting which is adjustable to vary the distance betweensaid rolls and said baffle being operatively connected to said mounting for movement con- 7 jointly with the mounting, and

means for producing a flow of air'through said residue removal ductwork with such air passing into said ductwork through said openings and flowing along said course in the direction of belt movement. 2. In combination with a flexible belt abrader including an endless belt with an abrasive material-removing outer face and roll support for such belt comprising a pair of spaced rolls having the belt trained thereover, means for guiding a workpiece against said belt in a zone where such is supported by one of said rolls with the belt curving about said one roll in regions on opposite sides of said zone,

power drive means for rotating the roll support for the belt whereby the belt travels from said zone about the curvature of said one roll and thence toward the other of said rolls in an outgoing reach of the belt,

residue removal ductwork comprising an elongate duct expanse including a wall portion extending the length of said outgoing reach in spaced opposition to the outer face of the belt in said reach, and duct wall structure extending between the lateral margins of said duct expanse and adjacent margins of said belt where it extends in said outgoing reach and including a wall portion facing the rear of said belt where it extends in said outgoing reach, whereby a substantially enclosed elongate course is defined which parallels and includes said reach of the belt,

said residue removal ductwork having an opening for air to travel into said course adjacent said zone and another opening in a region adjacent said other roll to accommodate additional flow of air into the ductwork, said ductwork further including an adjustable baffle which controls the size of said other opening, and

air mover means for producing a current of air through said course with such air moving in the direction of belt travel.

4. The combination of claim 2, which further includes an adjustable mounting for said other roll which is adjustable to vary the distance between said one and said other roll, and baffle segments adjacent opposite ends of said other roll which bend generally ,to follow the contour of the other roll and function to bound a portion of said course adjacent said other roll, said baffle segments being secured to the adjustable mounting for movement with the mounting.

5. The combination of claim 2, wherein said other roll is supported on an adjustable mounting which is adjustable to vary the distance between said other and said one roll, and said baffle is operatively connected to said mounting for adjustable movement with movement of said mounting. v a

6. In combination with a flexible belt abrader including an endless belt with an abrasive material-removing outer face and roll support for such belt comprising a pair of spaced rolls having the belt trained thereover,

means for guiding a workpiece against said belt in a zone where such is supported by one of said rolls with the belt curving about said one roll in regions on opposite sides of said zone, power drive means for rotating the roll support for the belt whereby the belt travels from said zone about the curvature of said one roll and thence toward the other of said rolls in an outgoing reach of the belt,

residue removal ductwork comprising an elongate duct expanse including a wall portion extending the length of said outgoing reach in spaced opposition to the outer face of the belt in said reach, said duct expanse further including a deflector spaced from said face of the belt where it curves about said one roll in traveling from said zone to said outgoing reach of the belt, said deflector in said duct expanse being adapted to ride against a workpiece guided against said belt in said zone and being movably mounted whereby it may follow the surface of the workpiece as it rides thereagainst, and duct wall structure extending between the lateral margins of said duct expanse and adjacent margins of said belt where it extends in said outgoing reach, whereby a substantially enclosed elongate course is defined which parallels and includes said reach of the belt, said residue removal ductwork having an opening for air to travel into said course adjacent said zone, and

air mover means for producing a current of air through said course with such air moving in the direction of belt travel. 

1. In combination with a flexible belt abrader including an endless belt with an abrasive material-removing outer face and roll support for such belt comprising a pair of spaced rolls having the belt trained thereover, means for guiding a workpiece against said belt in a zone of the belt adjacent where such belt is supported by one of said rolls, power-driven means for rotating the roll support for the belt whereby the belt travels from said zone and away from said one roll in an outgoing reach extending to the other of said rolls, residue removal ductwork comprising a duct expanse extending the length of said outgoing reach in spaced opposition to the outer face of the belt and forming a forward wall in said removal ductwork, wall structure disposed parallel to the rear of the belt in said outgoing reach and forming a rear wall in said ductwork, and additional side wall structure extending between said forward and rear walls to form a substantially enclosed course which encompasses said outgoing reach of the belt, said residue removal ductwork including an opening adjacent said zone for the inflow of air into said ductwork and another opening adjacent said other roll to accommodate additional flow of air into said ductwork, said other opening being defined by an adjustable baffle, said other roll being supported on an adjustable mounting which is adjustable to vary the distance between said rolls and said baffle being operatively connected to said mounting for movement conjointly with the mounting, and means for producing a flow of air through said residue removal ductwork with such air passing into said ductwork through said openings and flowing along said course in the direction of belt movement.
 2. In combination with a flexible belt abrader including an endless belt with an abrasive material-removing outer face and roll support for such belt comprising a pair of spaced rolls having the belt trained thereover, means for guiding a workpiece against said belt in a zone where such is supported by one of Said rolls with the belt curving about said one roll in regions on opposite sides of said zone, power drive means for rotating the roll support for the belt whereby the belt travels from said zone about the curvature of said one roll and thence toward the other of said rolls in an outgoing reach of the belt, residue removal ductwork comprising an elongate duct expanse including a wall portion extending the length of said outgoing reach in spaced opposition to the outer face of the belt in said reach, and duct wall structure extending between the lateral margins of said duct expanse and adjacent margins of said belt where it extends in said outgoing reach and including a wall portion facing the rear of said belt where it extends in said outgoing reach, whereby a substantially enclosed elongate course is defined which parallels and includes said reach of the belt, said residue removal ductwork having an opening for air to travel into said course adjacent said zone and another opening in a region adjacent said other roll to accommodate additional flow of air into the ductwork, said ductwork further including an adjustable baffle which controls the size of said other opening, and air mover means for producing a current of air through said course with such air moving in the direction of belt travel.
 3. The combination of claim 2, wherein said duct wall structure includes baffle segments adjacent opposite ends of said other roll which bend generally to follow the contour of the other roll and functioning to bound said course adjacent said other roll, the combination further including an exhausting duct that connects with said residue removal ductwork in the region of said ductwork adjacent said other roll.
 4. The combination of claim 2, which further includes an adjustable mounting for said other roll which is adjustable to vary the distance between said one and said other roll, and baffle segments adjacent opposite ends of said other roll which bend generally to follow the contour of the other roll and function to bound a portion of said course adjacent said other roll, said baffle segments being secured to the adjustable mounting for movement with the mounting.
 5. The combination of claim 2, wherein said other roll is supported on an adjustable mounting which is adjustable to vary the distance between said other and said one roll, and said baffle is operatively connected to said mounting for adjustable movement with movement of said mounting.
 6. In combination with a flexible belt abrader including an endless belt with an abrasive material-removing outer face and roll support for such belt comprising a pair of spaced rolls having the belt trained thereover, means for guiding a workpiece against said belt in a zone where such is supported by one of said rolls with the belt curving about said one roll in regions on opposite sides of said zone, power drive means for rotating the roll support for the belt whereby the belt travels from said zone about the curvature of said one roll and thence toward the other of said rolls in an outgoing reach of the belt, residue removal ductwork comprising an elongate duct expanse including a wall portion extending the length of said outgoing reach in spaced opposition to the outer face of the belt in said reach, said duct expanse further including a deflector spaced from said face of the belt where it curves about said one roll in traveling from said zone to said outgoing reach of the belt, said deflector in said duct expanse being adapted to ride against a workpiece guided against said belt in said zone and being movably mounted whereby it may follow the surface of the workpiece as it rides thereagainst, and duct wall structure extending between the lateral margins of said duct expanse and adjacent margins of said belt where it extends in said outgoing reach, whereby a substantially enclosed elongate course is defined which parallels and includes said reach of the belt, said residue removal duCtwork having an opening for air to travel into said course adjacent said zone, and air mover means for producing a current of air through said course with such air moving in the direction of belt travel. 